Do they weight 200gn? Are they 0.452" or larger diameter?
A hollowbase like that means you have to keep the velocity down. You go much about 850fps, and you will often get a 9-10 hole group from 5 shots or you'll stick a skirt and ring the barrel with your next shot.
Start low and stay low. You are aiming for very accurate loads at the 700-775fps range, so use a fast powder.
3.5-3.8gn N310
3.2-3.8gn Clays
3.1-4.0gn Bullseye
3.2-4.2gn AA2
3.5-4.2gn 700X
3.9-4.9gn 231/HP38
or such...